This application relates to measuring systems for objects and, in particular, for systems designed for making dimensional measurements on automotive vehicles for the purpose of collision damage repair. However, it will be appreciated that the principles described herein could have application to measurement of any type of object.
Various types of measuring devices have been used on vehicles, e.g., to attempt to determine how much a vehicle frame or body deviates from standard specifications in order to determine the amount of repair or straightening that may be needed. One such system is disclosed, e.g., in U.S. Pat. No. 6,115,927. That system utilizes a camera system for viewing and, thereby locating a hand-held probe. The system utilizes a dynamic reference frame to permit the system to accurately measure the three-dimensional coordinates of the probe, even if the camera is moved. The camera system consists of three individual camera modules or sensors on a bar. Each camera sensor cooperates with a processor to measure angles between the camera bar and electromagnetic radiation emitters or sources, such as LED's, on the dynamic reference frame and on the hand-held probe. From these angles, the measurement system calculates the three-dimensional coordinates of each emitter relative to the camera bar and, thereby, the position of the hand-held probe relative to the dynamic reference frame.
Each camera sensor must be able to see at least three emitters on the dynamic reference frame and at least two on the hand-held probe for the system to work. If any of the lines of sight between a camera sensor and an emitter is blocked, i.e., the emitter is not in the field of view of the camera sensor, the operator must diagnose the problem and fix it in order to enable optimal measurement readings. In this regard, the system provides a generic indication if a blockage exists between a camera sensor and a dynamic reference frame emitter, but there is no indication as to which components are blocked or how many. If there is a blockage of a hand-held probe emitter, an indicating signal appears on a display screen, but only after the operator attempts to take a reading by pressing the read button on the probe. There is no indication of a problem before attempting to take a reading, nor is there an indication as to which specific element or elements are blocked. It is known, in other fields, to provide an indicator on a probe to indicate whether or not the probe is in the field of view of a camera but, again, it does not provide the details of blockage in the event of plural emitter or sensor elements.